Railway traffic controlling apparatus



Oct 15, 1940. A. J. SORENSEN RAILWAY TRAFFIC conraonnms APPARATUS Filed March 30, 1940 INV ENTOR Andrew J 501 9121912.

Zdlw Hi5 ATTORN EY Patented Got. 15, 1940 RAILWAY TRAFFIC CONTROLLING APPARATUS Andrew J. Sorensen, Edgewood, Pa., assignor to The Union Switch & Signal CompamqSwissvale, Pa., a corporation of Pennsylvania I I ApplicationMarch 30,1940,SerialNo.321,015 A 11 Claims.

My invention relates to railway trafiic controlling apparatus; and it has particular reference to the organization of such apparatus into railway trafiic controlling systems of the class wherein coded trackway energy of the frequency code type is utilizedto control either or both wayside and train-carried cab signals.

In systems of the above described class, track- Way energy coded at one or another of a plurality of distinctive code rates is supplied to the rails of a trackway for selectively controlling a traffic governing device in accordance with the rate at which such energy is coded. This selective control of the traffic governing device ordinarily is established through the medium of a tractive armature type code following relay, which operates its armature in response to each code period of energy received from the track rails, and a plurality of decoding relays one for each of the different rates of coding. The decoding relays are utilized to. establish one or another of a plurality of circuits for the governing device in accordance with the particular relay or combination of such relays energized, and suitable decoding units, such as electrical filters, are employed to condition .the decoding relays to be selectively energized in accordance with the rate of operation of the code following relay.. In such systems, the rates of coding the trackway energy are limited. to a large extent to those rates which enable a code responsive relay to operate its tractive, armature properly in response to each period of coded energy. Accordingly, relativelylow code rates, such, for example, as 75, l20,and 180 cycles per minute, are employed since it has been found that such rates best enable a tractive armature type code following relay to operate properly.

In view of the fact thatsystems' of the'above described class heretofore proposed utilize circuitsincluding electrical filters to selectively energize the decoding relays in accordance with the rate at which the code following relay operates, and since the size and cost of such filters increase rapidly as the frequency for which the filter is designed to select and pass is decreased, such systems have been designed to tune or filter only the circuits of the higher code rates and leave untuned the circuit of the lowest code rate. This, then, requires that the more rapid code rates be utilized to control the less restrictive control functions of the governing device and the lowest code rate be utilized to control a more restrictive function, inasmuch as a check upon the operativeness ofthe filters isrequired from the standpoint of safety to preve'rit y possi bility of false clear failures due to a'failure' of the decoding units. Accordingly, such systems are designed so that the most rapid code rate, usually the 180 code, is utilized to control the trafiic governing device to its cl'ea r or'le'ast restrictive condition; the intermediate or 120 code is employed to control the device to its approach medium condition; the lowest 'or75 code is used to control the device to its caution or most restrictive proceed condition; and the stop or most restrictive'condition of the de vice is caused to be controlledbyan absence of the trackway energy. Inasmuchas each section of the trackway normally is occupied only for a relatively short interval of time, the most rapid code is the most prevalent in the track rails of such systems and as a result the coderesponsive relay is caused tooperate normally at its most rapidrate. V A A It' is an object of my invention to provide a railway tralfic controlling system of the frequency code type incorporating novel and improved means for utilizing the lowest rate of coding to I control the least restrictive control function of a traffic governing devicethereby enabling the code responsive relay ,to operate normally at its lowest rate. V

Anothenobject of my invention -is the provision of novel. and improved railwaytraflic con trolling systems, of the frequency code class, in whichthe'apparatus is arranged: in such manner that the least restrictive control function of a traffic governing device is governed by the lowest code rate, and wherein all the usual safety features of thefrequency code systems are retained to prevent the possibility of such systems controlling a less restrictive function of suchdevice than should be controlled under the particular I code conditionsinthe trackway.

A further object of my invention is the provision, in railway trafiic controlling systems of the frequency-code class, of novel and improved decoding means involving no electrical filters or tuned circuits, for selectively controlling one or another of a plurality of control functions of a traffic governing device in accordance with the rate at which trackway energy received from the track rails is coded. I

The above mentioned and other important objects and characteristic features of my invention which will become readily apparent from the following description, are "attained in accordance with my invention by reversing the relativepolarities of magnetic mm in a magnetizable core at a rate corresponding to the rate of operation of a code responsive relay, and by employing a plurality of decoding relays one for each of the rates of coding selected to be detected. These decoding relays are energized in series with the windings which are mounted on the core and which when energized effect the reversal of flux in the core, and the relays are proportioned and designed in such manner that each relay responds to the current flow through its winding only when the rate of interruption of such current does not exceed the code rate that such relay is assigned to detect. A traflic governing device also is provided and is selectively controlled by the decoding relays.

The invention further consists in the parts and in the arrangement and'organization of such parts into railway traffic controlling systems, as will be pointed out more clearly hereinafter.

I shall describe two forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view illustrating a preferred form and arrangement of apparatus embodying my invention. Fig. 2 is a diagrammatic view illustrating a modification of the apparatus shown in Fig. 1, and also embodying my invention. In each of the two views of the drawing. similar reference characters have been employed to designate corresponding parts.

In the particular embodiment of my invention illustrated in Fig. 1, apparatus embodying my invention is shown applied to a four-indication cab signal system wherein selective control of a train-carried cab signal is established in accordance with the rate at which energy inductively received from the rails of a trackway is coded. Referring now to Fig. 1, the reference characters I and la designate the track rails of a stretch of trackway, which rails are supplied with trackway energy coded at one or another of the customary plurality of code rates. The wayside apparatus which supplies coded energy to the rails l and la is not shown in the drawing since it forms no part of my present invention, but such apparatus may take any one of the well-known forms employed in what is known as three block, four-indication frequency code signal systems, effective to supply the rails of the trackway with energy which is coded at one or another of three different rates of coding in accordance with traffic conditions in advance. For the purposes of this description, I shall assume that the rails l and la are supplied by such wayside apparatus with alternating trackway energy which is coded or periodically interrupted at a rate of '75, 120 or 180 times per minute. However, contrary to the usual practice, I shall assume that the wayside apparatus is so controlled by trafiic conditions in advance that the lowest or '75 code rate is supplied to the rails I and la under clear traffic conditions of the stretch; that the intermediate or 120 code is supplied under approach medium trafilc conditions; and that the highest or 180 code is supplied under approach traffic conditions in the stretch.

The trackway energy supplied to the rails l and la is inductively picked up by the usual two receiving coils 4 and 5, which coils are carried .on the locomotive in front of its first pair of wheels and which are connected together in series in such manner that when electromotive forces are induced therein in response to alternating current of opposite instantaneous polarities in the rails I and la, such forces are additive. The two coils 4 and 5 are connected through the medium of the usual amplifier A to a master code responsive relay MIR.

The reference characters DR. with suitably distinguishing suflixes designate decoding relays which are designed and proportioned, as will be made clear presently, to respond selectively to current supplied to the operating windings of such relays when and only when such current is of a predetermined magnitude. As shown, these relays are of the polar relay type, and are magnetically biased to operate their armature to one position or another in accordance with the polarity of flux set up by current supplied to their operating windings. Such magnetic bias may be established in the relays, as shown, by constantly energizing a winding 1 provided for each relay, or if desired, the magnetic bias may be established in the relays through the medium of one or more permanent magnets, in which latter event, of course, the windings I could be dispensed with. The relays DR. are provided with two operating windings 8 and 9, one winding 8 being efiective when energized with current of a predetermined magnitude to operate the associated armature to its normal or left-hand position, as viewed in Fig. Land the other winding 9 being effective when energized with current of a predetermined magnitude to operate the associated armature to its reverse or righthand position, as viewed in Fig. l. Preferably, there is a decoding relay DR for each code rate of the trackway energy but one.

. The reference character DT designates a decoding transformer having a magnetizable core upon which are mounted a pair of primary windings I! and I2, and which core also is provided with a plurality of secondary or output windings one for each of the rates at which the trackway energy is coded. One primary winding ll of transformer DT is connected in series with one operating winding 8 of each decoding relay DR over a circuit which will be pointed out in detail presently, and the other primary winding !2 of transformer D1 is connected in series with the other operating winding 9 of each decoding relay DR over a circuit shortly to be traced.

The reference characters R with suitably distinguishing suffixes designate code detecting relays, there being one relay for each of the code rates of the trackway energy. I

The reference character CS designates a cab signal having a plurality of signal indication units one for each code rate of the trackway energy and also one indication unit for indicating that no energy is being received from the track rails. As shown, the signal indication units of signal CS comprise four signal lamps 34, 35, 3B and 31, which lamps when illuminated display distinctive aspects which I shall term clear, approach medium, approach and stop, respectively.

Having thus described the various parts of the apparatus embodying my invention, I shall now describe the manner in which such apparatus responds to each code condition in the trackway, and shall at the same time trace the circuits over which the several parts of the apparatus are controlled.

I shall assume first that a train provided with apparatus embodying my invention and hereinbefore described is traversing a stretch of trackway which is Supplied with trackway Y ener y coded at one or another of the '75, 120 or 180 code rates. Under such assumed conditions, the trackway energy picked up by the coils 4 and 5 and supplied to relay MR causes that relay to operate its armature at a rate corresponding to the rate at which the picked-up energy is coded, to reverse the polarity of flux in transformer DT at a rate corresponding to the rate of operation ofrelay MR. That is to say, relay. MR operates its armature from one position to another on the supply of energy from the coils 4 and .5,"and operates its armature from the other position back to the one position on the interruption of such supply of energy. In one position of relay MR, one of the primary windings of transformer DT is sup-plied with unidirectional current in series with one operating winding of each of the decoding relays, over a circuit which-may be traced from one terminal B of a suitable source of unidirectional current; such as a battery not shown, through windings 8 of relays DRI and DR2, respectively, primaryfwinding II of transformer DT, and contact I8I9 of relay MR closed in the left-hand position of the armature of relay MR (as viewed inthe drawing) to the other terminal C of the source of current. As

shown, a condenser I! may be connected across' contact I8I9 of relay MR to suppress sparking at such contact. Relays-DRI and DR2 are constantly supplied with biasing magnetic flux due to unidirectional current supplied over an obvious circuit to windings I of relays DRI and DR2, respectively, and I shall assume that windings I and 8 are disposed on the magnetic circuits of the decoding relays DR in such manner that the resultant flux established in' each of the decoding relays due to current in windings I and 8 tends to cause its associated movable contact member or armature to be operated to its left-hand position, as viewed in the drawing. I shall further assume that winding II is disposed on the core of transformer DT in such manner that current in this winding creates flux of what I shall term normal polarity in the core of the transformer.

In the other or right-hand position of the armature of relay MIR, as viewed in the drawing, the other primary winding of transformer DT is energized in series with the other operating winding of each decoding relay over a circuit which extends from terminal B through windings 9 of relays DRI and DR2, respectively, primary winding I2 of transformer DT, and contact 20I9 of relay MR to terminal C. A condenser 2| is connected, as shown, across contact 20I9 of relay MR to suppress sparking at such contact. Windings 9 are disposed on the magnetic circuit of the 'decodingrelaysDR in such mannerthat the resultant flux established in each of the decoding relays due to current in windings I and 9 tends to cause its movablecontact member to be operated to'its right-hand position, as yi'ewedin the drawing; and winding I2 is mountedfon the core of transformer DT in such manner that current 'inthis winding creates flux opposite in polarity to that due to current in winding I I. It follows, therefore, that windings II'and I2 of transformer DT are alternately energizedto .reverse'the po larity of flux in transformer .DT at a rate corresponding to the rateof operation .of relay MR, and also that windings 8 and 9 of each'of "the decoding relays DRIand DR2 are energized alternately at a rate; corresponding to the rate'of operation of relay MR, fwhereby under certain conditionslater to be setforth in -detail, such 7 decoding relays are selectively caused to operate their respective armatures at a rate corresponding to the rate of operation of relay MR. Y I

' Code detecting relay RI is connected through the medium of pole changing contacts 22-23 and 22-24 of relay DRI to secondary winding I4 of transformer DT; relay R2 is connected through pole changing contacts 26-2I and 26-28 of relay DR2 to secondary winding I5 of transformer DT; and relay R3 is connected through pole changing contacts 3IJ-3I and 30-32 of relay MR to secondary winding I6 of transformer DT. As is readily apparent from an inspection of the drawing, the operation of the pole changing contacts of relays DRI,'DR2 and-MR effects rectification of the alternating current induced in secondary windings I4, I5 and I6, respectively, of transformer DT due to the periodic reversals of flux in transformer DT, and as a result relays RI, R2 and R3 are energized, respectively, when the pole changing contacts interposed in circuit with each of such relays are periodically operated to cause substantially unidirectional current to be supplied to such relays.

The code detecting relays RI, R2 and R3 establish selective control over signal CS'in' accordance with the particular relay or combination of such relays caused to be. energized. When relays RI, R2 and R3 are all energized, signal CS is caused to display its clear aspect over a circuit extending from terminal B through front contact 39 of relay R3, front contact 40 of relay R2, front contact M of relay RI and the filament of unit 34 of signal CS to terminal 0.

" In the event that relays R2 and R3 are energized and relay RI is deenergized, signal CS is caused to display its approach medium aspect over a circuit which extends from terminal B through front contact 39 of relay R3, front contact 40 of relay R2, back contact 42 of relay RI and'the filament of unit 35 of signal-CS to terminal C. I

' If, however, only relay R3 is energized, then signal CS displays its approach aspect in respose to the energization of unit 36 over a circuit which extends from terminal B through front contact 39 of relay R3, back contact 43 of relay R2 and the filament of unit 39 of signal CS to terminal C.

Whenever relays RI, R2 and R3 are all released, signal CS is caused to display its stop aspect over asimple circuit including terminal B, backcontact 44 of relay R3, the filament of unit 31 of signal CS and terminal C.

The above described control of signal CS is effected by the apparatus illustrated in Fig. 1 by proportioning the decoding relays DR with respect to the parts of transformer DT in such manner that the decoding relays are selectively responsive to and each follows the alternate energization'of its two operating windings when and only when the alternate energization of such windings occurs at a rate not in excess of a predetermined maximum rate. Thus, for example, relays DRI and DR2 may be designed and proportioned so that when relay MR responds to 15 code received from the trackway, the current that is supplied alternately first to operating windings 8of the decoding relays in series with. primary winding I I of transformer DT, and then to operating windings 9 of such relays in series with primary winding I2 of transformer DT, is of sufiicient magnitude to cause both decoding relays to respond and operate at a rate corresponding to the rate at which relay MR operill (ill

ates. RelayRI accordingly is caused to be energized and picked up in response to the action of the pole changing contacts 2223 and 22--24 of relay DRI rectifying the current induced in seccndary winding, I 4 of transformer DT and sup--' plied over the contacts of relays DRI to relay RI; relay R2 is caused to be picked up in response to .he substantially unidirectional current supplied .rom secondary winding I of transformer DT "o relay R2 over contacts 26-21 and 26-28 of relay DR2; and relay R3 also is picked up in response to the substantially unidirectional current supplied from secondary winding I6 of transformer DT to relay R3 over contacts 30-3I and 30-32 of relay MR. It can be seen, therefore, that with relays RI, R2 and R3 picked up in response to relay MR following '75 code, signal CS is caused to display its clear aspect whenever the lowest code rate is received from the trackway.

When the frequency of the alternate energizations of the two operating windings of the decoding relays is increased due to relay MR respond ing to an increased rate of coding of the trackway energy picked up by the coils 4 and 5, the frequency of the alternate energizations of windings Ii and I2 of transformer D1 is correspondingly increased to effect a similar increase in the rate of reversals of flux polarity in the core of the transformer. As a result of the increased rate of alternate energization of the primary windings II and I2 of transformer DT, and of the increased frequency of reversals of flux in the transformer core, there is an increase in the impedance of the primary windings, and a corresponding decrease in the flow of current through these windings. If, now, relay MR operates at a rate in excess of the predetermined rate of operation of relay DRI, the alternate energization of windings II and I2 of transformer DT and the consequent reversals of flux in the transformer core, which occur at a rate corresponding to the rate of operation of relay MR, cause the impedance of windings II and I2 to build up w to a value such that the current flow through windings II and I2 of transformer DT and operating windings 8 and 9 of relays DRI and DR2 is insufiicient to cause relay DRI to operate its movable contact member 22. This contact accordingly remains in its last operated position and does not function to rectify the current supplied from secondary winding I4 of transformer DT to relay RI. Relay RI accordingly is energized with alternating current supplied from a portion of winding I4, and consequently relay RI remains released until such time as the rate of operation of relay MR decreases to a degree such that the rate of operation of relay MR is not in excess of the predetermined rate of operation of relay DRI.

To accord with the hereinbefore assumed rates of 75, 120 and 180 code, I shall assume that relay DRI is designed to respond to and follow the operation of relay MIR when and only when relay MR operates at a rate not materially in excess of 75 cycles per minute, and shall also assume that relay DR2 is designed to respond to and follow the operation of relay MR when and only when relay MR operates at a rate not materially in excess of 120 cycles per minute.

Under the above assumed conditions, it can be seen, that when relay MR responds to 120 code picked up by coils 4 and 5 from the rails of the trackway, decoding relay DR2 only responds to the operation of relay MR and code detecting relays R2 and R3 only are energized. Signal CS accordingly is caused to display its approach medium aspect when the intermediate code is received from the rails of the section.

If, however, relay MR responds to 180 code received from the rails of the trackway, then both decoding relays DRI and DR2 retain their armatures in their last operated position so that relays RI and R2 are released. Relay R3 is energized in-response to the operation of contact member 30 of relay MR rectifying the alternating current induced in secondary winding I8 of transformer DI' into substantially unidirectional current, and as a result signal CS is caused to display its approach aspect due to the illumination of signal lamp unit 36.

In the event that the train equipped with apparatus embodying my invention is following another train in a section, then the coded trackway energy is shunted away from such following train and relay MR retains its movable contact members I9 and 30 in their last operated position. Under suchassumed conditions, unidirectional current is constantly supplied to one primary winding of transformer DT in series with one operating winding of each of the decoding relays, and as a result no electromotive forces are induced in secondary windings I4, I5 and I6 of transformer D'I' so that relays RI, R2 and R3 are all released to control signal CS to its stop indication due to the energization of signal unit 31.

In Fig. 2 is shown a modified arrangement of the apparatus illustrated in Fig. 1, wherein the energizing circuits of relays DRI and DR2 are so arranged that relay DRI operates its movable contact member only in response to code of 75 cycles per minute or less, and relay DR2 operates its movable contact member only when relay MR responds to energy coded at a rate in excess of 75 cycles per minute but not greatly in excess of 120 cycles per minute. Referring now to Fig. 2, it can be seen that winding 9 of relay DR2 is connected in circuit with primary winding I2 of transformer DT and with winding 9 of relay DRI only when relay RI is released to close its back contact 41, and that when relay RI is picked up in response to the operation of relay DRI when master relay MR follows '75 code received from the trackway, front contact 46 of relay RI completes a circuit path wherein winding 9 of relay DR2 is replaced by a resistor 48. This resistor is selected to match or equal the resistance of winding 9 of relay DR2 and thus compensate for the resistance of such winding when it is cut out of circuit with winding 9 of relay DRI and winding I2 of transformer DT.

With the apparatus arranged as shown in Fig. 2, relay DRI is caused to operate when relay MR responds to '75 or a lower code rate, but relay DR is not-operated on 75 code since relay RI is controlled to remove winding 9 of relay DR2 from the circuit of winding I2 of transformer DT, consequently relay DR2 is energized only by impulses intermittently supplied to its winding 8 and accordingly its armature is retained in the position to which it is operated due to the resultant of the fluxes set up by windings I and 8 of relay DR2. When, however, relay DRI ceases to operate due to relay MR following a code more rapid than 75 cycles per minute, then relay RI is released to connect winding 9 of relay DR2 in circuit with primary winding I2 of transformer DT, and windings 8 and 9 of relay DR2 are alternately energized to cause the operation of the associated polar armature if relay MR operates at a rate not materially in excess of 120 cycles per minute. It can be seen, therefore, that since relay DRI operates only in response to .75 code or less, and relay DR2 operates in response to codein excess of 75 cycles per minute but not materially in excess of 120 cycles per minute,

only one of the two decoding relays DR is caused to operate at any one time.

With the apparatus arranged in the manner illustrated in Fig. 2, relays RI andR3 are energized and relay R2 is deenergized when relay MIR. follows 75 code, as shown in Fig. 2; relays R2 and R3 are energized and relay RI is deenergized when relay MR follows 120 code; and relay R3 only is energized when relay MR follows 180 code. In order, therefore, to control signal CS in a manner corresponding to the control established over the signal by the apparatus illustrated in Fig. 1, signal OS of Fig. 2 is caused to display its clear indication over an obvious circuit including front contact 4| of relay RI andthe filament of unit 34 of signal CS of Fig. 2; the approach medium aspect of signal CS of Fig. 2 is displayed when unit 35 of signal CS is energized over a circuit passing from terminal B through back contact 42'0f relay RI, front contact of relay R2 and. the filament of unit 35 of signal OS to terminal C; the approach aspect of signal CS of Fig. 2 is caused to be displayed when a circuit is completed from terminal B through back contact 42 of relay RI, back contact 43 of relay R2, front contact 39 of relay R3 and the filament of unit 36 of signal OS to terminal C; and the stop indication of signal CS of Fig. 2 is displayed when unit 3! of signal CS is energized over a circuit which extends from terminal B through back contact 42 of relay RI, back contact 43 of relay R2, back contact 44 of relay R3 and the filament of unit 31 of signal CS to terminal C.

From the foregoing description of the operation of the apparatus of Figs. 1 and 2, it is readily apparent that I have provided apparatus which is selectively responsive to each of a plurality of different rates of codingand wherein each of the different rates is detected without utilizing elec-. trical filters such as have been proposed heretofore. It, is also apparent that such apparatus is arranged on the closed circuit principle insofar as afailure of a portion of the apparatus to operate properly cannotv cause the apparatus to control a less restrictive function than should be controlled. It follows-therefore, that apparatus embodying my invention permits the lowest code rate to be utilized to'control the least restrictive control aspect, inasmuch as there is no need to detect a failure of electrical filter elements such as have been proposed for use in coded systems of the type employing frequency codes, hence a failure of theapparatus to respond properly to the-higher code rates cannot operate to cause the apparatus to establish control over a less restrictive aspect than should be displayed by such code rates.

' An advantage of apparatus embodying my invention is that by utilizing the lowest code rate to control the least restrictive function of a traffic governing device, a system is provided wherein the parts normally operate at their lowest rate, thereby avoiding undue wear of the parts and tending to prolong the life of such apparatus. In addition, the relatively expensive electrical filter units such as have been considered necess'ary heretoforeare dispensed with, 'thus reducingthe initial and maintenance cost of such code signal system. Furthermore, since the lowest code rates control the least restrictive aspects, there is no tendency for harmonics of such lower code rates, such as might be present due toa limping operation of a code transmitter and/or of the code responsive relay, to cause the apparatus to be controlled to a less restrictive aspect than should be controlled by suchlow code rates.

It is to be understood, of course, that while my invention has been described in connection with a four-indication cab signal system responsive to trackway energy coded at 75, 120 and 180 cycles per minute, my invention is in nolw'ay limited to the illustrated system but may, be em:-

ployed to control any desired number of indicae tail heretofore. It is, of course, assumed that suit-.-

able Wayside apparatus will be provided for. such systems to supply the rails of the trackway with energy coded at one or another of a plurality of n rates of coding, and that the frequenciesiof such rates are in the range suitable for use in,

code railway signal systems.

Although I have herein shown anddescribed only two forms of railway trafiic controllingap paratus embodying my invention, it is under stood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Decoding apparatusfor use with a stretch of trackway which is supplied with trackway energy coded at one or another of a plurality of code rates, comprising the combination of a code responsive relay operated by energy received fromthe railsfiof the trackway, a. reactor, a plurality of relays, one for detecting each of said code rates, a series circuit including a winding of each of said [relays and reactor and periodically supplied with current over a contact of said code respon sive relay, .said relays being proportioned with respect to said reactor in su ch manner as to-be selectively responsive to the periodic energizaitions of their windings when and only when such energ-izations occur at a rate not in excess of the rate to be detected by such relays, and railway tnaffic controlling apparatus selectively controlled by said relays.

. 2. Decoding apparatus for use with a stretch of trackway which is supplied with tnackwiay energy other in response to each code period ofenengy' received from the rails of the trackway, a plufnality of two-winding relays one for detecting each of said code rates, a reactor, two circuits, one

includingin series one winding of each of saidrelays and said reactor and the other circuit in eluding a series the other winding of each of said relays and said reactor, a source of unidirectional current connected alternately to first one and then the other of said two circuits over cont-acts of said code responsive relay, said relay windings being proportioned with respect to saidreactorin suchmanner as to effectively energize the relays when and only when the alternate energizations of such windings occur at a rate not in excess of the rate to be detected by such relays, and railway .traflic controlling apparatus selectively controlled by saidrelays. h

i 3. In combination, a code responsive relay, means for operating saidrelay at one or another of a plurality of preselected rates of coding, a reactor, a plurality of relays one for detecting each of said code rates, a circuit including a winding of each of said relays and said reactor and periodically supplied with current over a contact of said" code responsive relay, said relays being proportioned with respect to said reactor in such manner as to be selectively responsive to the magnitude of current in said circuit when and only when said code responsive relay operates at a rate not in excess of the rate to be detected by such relays, and railway trafiic controlling apparatus selectively controlled by said relays.

4. Decoding apparatus for use witha trackway which is supplied with trackway energy coded at one or another of a-plurality of different rates of coding, comprising the combination of, a code responsive relay operable by coded energy received from the rails of said trackway, a magnetizable core, a pair of primary windings mounted-on said core, a plurality of two-winding relays one fordetecting eachof said plurality of code rates, a first circuit including in series one of said primary windings and one winding of each of said decoding relays, a second circuit including in series the other of said primary windings and the other winding of each of said decoding relays, means controlled by said code responsive relay for supplying unidirectional energy alternately to first one and thenlthe other or said two circuits, the polarity of the unidirectional energy supplied to said two circuits being selected with respect to said two primary windings in suchlrranner that the two windings create opposing fluxes in said magnetizable core, the win-dings of said decoding relays being arranged and proportioned with respect to said two primary windings and said magnetizable core in such manner that each decoding relay is operated in response to the alternate energizaxtions of its two windings when and only when the frequency of alternate energization of such winding-s does not exceed the code rate which such decoding relay is designed to detect, and a railway traflic controlling signal selectively controlled by said decoding relays.

5. Decoding apparatus of the class adapted for use with a stretch of trackway which is supplied with tra-ckway energy coded at one or another of a plurality of different rates of coding, comprising the combination with Ia code responsive relay operated by energy received from the rails of the tnackway, of a plurality of two-winding decoding relays one for detecting each of said plurality of code rates, a magnetizable core provided with a primary winding having two portions, two circuits a first circuit of which includes in series one portion of said primary winding and one winding of each of said decoding relays and the second circuit of which includes in series the other portion of said primary winding and the other winding of each of said decoding relays, a source of unidirectional current, means controlled by said code responsive relay for connecting said source alternately to one and then the other of said two circuits in such manner that currents in said two portions of said primary winding create opposing fluxes in said magnetizable core; the windings of said decoding relays being designed and proportioned with respect to said primary winding and said magnetizable core in such manner that each decodingrelay-is operated in response to the alternate energizations of its two windingswhen and only when such alternate energizations occur at a rate which does not exceed the code rate that such relay is designed to detect, and railway traflic controlling apparatus selectively controlled by said decoding relays. a,

6. In combination with a code responsive relay and a decoding transformer having a magnetizable core provided with a primary winding divided into two portions, a plurality of two-winding decoding relays one for detecting each of a plurality of different rates of coding, two circuits a first circuit of which includes in series one portion of said transformer primary winding and one winding of each of said decoding relays and the second circuit of which includes in series the other portion of said transformer primary winding and the other winding of each of said decoding relays, a source of unidirectional currentnreans controlled by said code responsive relay for connecting said source alternately to first one and then the other of said two circuits in such manner that current in said two portions of said transformer primary winding create opposing fiuxes in said transformer core, the wind ings of saiddecoding relays being designed and proportioned with respect to said transformer primary winding .and said transformer core in such mannerthat each decoding relay is operated in responseto the alternate energizations of its two windings when and only when such alternate energizaitions occur at arate which does not exceed the code rate that such relay is designed to deteot, and railway trafliccontrolling apparatus selectively controlled by said decoding relays.

, 7, In combination-with a code responsive relay and a decoding transformer having a magnetizable core provided with a primary. winding dividedinto two portions, a plurality of two-winding polar relays one'for detecting each of a plurality of different rates of coding, two circuits a first circult of which includes inseries one portion of said transformer primary winding and one winding of each of said polar relays and the second circuit of which includes in series the other portion of said transformer primary. winding and the other winding. of each of :said polar relays, a source of unidirectional current, means controlled by said code responsive relay for connecting said source alternately to one and then the other of said two circuits in such manner that currents in said two portions of said transformer primary winding create, opposing fluxes in saidtransformercore and currents in said two windings of said polar relays tend to cause the polar armatures of said relaysto operate'in opposite directions, the windings of said polar relaysbeing designed and proportioned with respect to said transformer primary winding and said transformercore in such manner that each, polar relay operates its polar armature in response to the alternate energize,- tions of its two windings when and only when such alternate energizations occur at a rate which does not exceed the code rate that such relay is designed to detect, and railway traflic controlling apparatus selectively controlled by said polar relays. i

H 8. In combination with a code responsive relay and a decoding transformer having a magnetizable core provided with a primary winding divided into two portions, said transformer having a plurality of secondary windings one for each of a plurality of different rates of coding, a plurality of two-winding decoding relays one for detecting each of a plurality of different rates of coding and each having a polar armature, two circuits a first circuit of which includes in series one portion of said transformer primary winding and one winding of each of said decoding relays and the second circuit of which includes in series the other portion of said transformer primary winding and the other winding of each of said decoding relays, a source of unidirectional current, means controlled by said code responsive relay for connecting said source alternately to one and then the other of said two circuits in such manner that currents in said two portions of said transformer primary winding create opposing fluxes in said transformer core and currents in said two windings of said decoding relays tend to cause the polar armatures of said relays to operate in opposite directions, the windings of said decoding relays being designed and proportioned with respect to said transformer primary winding and said transformer core in such manner that each decoding relay operates its polar armature in response to the alternate energizations of its two windings when and only when such alternate energizations occur at a rate which does not exceed the code rate that such relay is designed to detect, a plurality of direct current control relays one for each secondary winding of said transformer, means controlled by each of said decoding relays for selectively connecting said control relays to said secondary windings in such manner that each of said control relays is supplied with unidirectional energy from its associated secondary winding when and only when the decoding relay connecting such control relay to its secondary winding is operating its polar armature, and a railway signaling device selectively controlled by said control relays.

9. Railway traffic controlling apparatus comprising, in combination, a magnetizable core provided with a plurality of secondary windings and having a primary winding divided into two portions, means for supplying unidirectional current alternately to first one and then the other of saidtwo portions of the primary winding in such manner that the flux due to current in one portion opposes the flux due to current in the other portion, said core and said primary winding being proportioned so that throughout a range of frequencies of alternate energization of the two portions of said primary winding the flow of current in said portions is inversely proportional to the frequency of reversals of flux in said core, a plurality of decoding relays one for each of said secondary windings and each having two operating windings one interposed in series with said one portion of the primary winding and the other interposed in series with said other portion of the primary winding, said decoding relays being proportioned to respond selectively to the magnitude of current in said two operating windings, and a plurality of control relays one connected to each of said secondary windings over pole changing contacts of the associated decoding relay.

10. In combination with a decoding transformer provided with a magnetizable core having a plurality of secondary windings and having a primary winding divided into two portions adapted to be supplied alternately with unidirectional current in such manner as to induce electromotive forces in said secondary windings, a plurality of windings and each having two-operating Windings, aplurality of control relays one connected to each of said transformer secondary windings f over pole changing contacts of the associated decoding relay, a circuit for one portion of said transformer primary winding including in series a selected one operating winding of each of said decoding relays, and a circuit for' the other portion of said transformer primary winding including in series the other operating winding of each of said decoding relays, said decoding relays being designed and proportioned with respect to the parts of said transformer in such manner that each decoding relay operates its pole changing contacts when and only when its two windings are energized alternately at a rate not exceeding a predetermined rate.

11. In combination with a decoding transformer provided with a magnetizable core having a,

plurality of secondary windings and having a primary winding divided into two portions adapt ed to be supplied alternately with unidirectional current in such manner as to induce electromo tive forces in said secondary windings, a plurality of decoding relays one for each of said secondary windings and each having two operating windings,-a plurality of control relays one connected l to each of said transformer secondary windings,

over pole changing contacts of the associated decoding relay, a circuit for one portion of said transformer primary winding including in series a selected one operating winding of each of said decoding relays, and a circuit for the other portion of said transformer winding including the other operating winding of one of said decoding relays connected in series with a resistor or with the other, operating winding of another of said decoding relays accordingas the control relay associated with said one decoding relay is picked up or released, said decoding relays being designed and proportioned with respect to the parts of said transformer in such manner that each decoding relay operates its pole changing contacts when and only when its two windings are energized alternately at a rate not exceeding a predetermined rate.

. ANDREW J. SORENSEN.

15 decoding relays one for each of said-secondary 

